It is generally known to use contact lines alongside trailing cables if movable electric consumers—such as, for example, crane travelling trolleys having an electric travelling drive and an electric lift drive—have to be supplied with electric energy. Other areas of application are current supplies for cranes, monorail systems and feeding and processing machines.
German patent DE 198 07 792 C2 discloses a connector for two successive contact lines. Contact lines of this type consist substantially of a longitudinal plastics profile which is formed as a hollow profile having a c-shaped cross-section and an inner space produced therefrom. By reason of the c-shaped cross-section, the longitudinal plastics profile includes a longitudinal gap which extends in the longitudinal direction of the longitudinal plastics profile. Typically, the longitudinal plastics profile is suspended in such a manner that the longitudinal gap faces downwards and the longitudinal plastics profile is thus open at the bottom. Disposed in the inner space of the longitudinal plastics profile are holding elements which extend in the longitudinal direction of the longitudinal plastics profile and into which contact lines consisting of copper are fed. The movable electric consumers are supplied with current or control signals via the contact rails. For this purpose, a current collector trolley in the inner space of the longitudinal plastics profile is movable in and opposite to the longitudinal direction of the longitudinal plastics profile via rollers on tracks in the inner space of the longitudinal plastics profile. Disposed on the current collector trolleys are, on the one hand, contact line contacts and on the other hand, an electric line which is guided outwards to the electric consumer via the longitudinal gap. The contact line contacts are in contact in each case with one of the contact rails in a resiliently pretensioned manner.
In order to connect the ends of two contact lines, the ends of the contact rails protruding out of the ends of the longitudinal plastics profiles are initially connected together via contact rail connectors. In this case, a transverse gap remains between the ends of the longitudinal plastics profiles, in order to be able to equalise the mutually different thermal expansions of the contact rails and the longitudinal plastics profiles. Then, a connector is used which is divided transversely into two housing halves and which essentially has the task of providing protection against contact in relation to the contact rail connectors, permitting any different thermal expansions of the contact rails and the longitudinal plastics profiles and bridging a gap between the ends of the longitudinal plastics profiles in the region of the tracks for the current collector trolleys. The housing halves of the connector are slid onto the opposite ends of the plastics profiles which are to be connected, then the contact rails are connected via the contact rail connectors and subsequently the two housing halves are pushed towards each other, until they are connected together via latching connections and reliably bridge the contact rail connectors. The mutually connected housing halves remain displaceable relative to the two connected plastics profiles within specified limits, in order to be able to equalise any thermal changes in length of the plastics profiles. In order to ensure that the connector is able to fulfill its aforementioned objectives, slots, long holes, recesses and protrusions are provided at the ends of the plastics rails. The long holes serve to attach the housing halves of the connector to the plastics profiles in such a manner as to be displaceable relative to the two connected plastics profiles within specified limits. The recesses and protrusions cover the transverse gap in the region of the track between the two plastics profiles. The slots serve to electrically insulate the holding parts of the mutually adjacent contact rail connectors.
Furthermore, U.S. Pat. No. 2,961,499 discloses a further arrangement for connecting contact line rails. The contact line rails consist substantially of several contact rails which extend in parallel with each other and which are disposed in a sheet metal cover rail which is open at the bottom. In order to connect the ends of the contact rails electrically to each other, contact rail connectors are provided which are attached in a clamping manner to the ends of the contact rails and in the centre of which there is disposed a flexible region which is formed as a flexible wire. The cover rail, as seen in the longitudinal direction thereof, consists of individual portions which are screwed together via u-shaped connection elements. For this purpose, each of the connection elements has approximately the contour of the cover rail, can be inserted in the region of one end into the cover rail until this portion of the cover rail can be screwed to the connection rail and a sufficient length of the connection element protrudes out of the cover rail, in order to attach the subsequent portion of the cover rail and screw it fixedly thereto. A shorter portion of the cover rail can also be disposed in the region of the contact rail connector and can thus assume the function of a cover in the region of the contact rail connector.